Polychrome screen and process for making same.



` C. L. 11E 'BRASSBUIL POLYGHEOME SCREEN AND PROCESS EOE MAKING SAME;

I APPLICATION FILED OGTA, 1907.

976,111.8., 1 Patented Nov. 15, 1910.

Iliih /yf y `New York and State of New ITE i CHARLES L. A. BRASSEUR, OF NEW YORK, N. Y.

POLYCHROME SCREENV AND PROCESS FOR MAKING SAME.

ovaire. Y

Specification of Letters Patent. Patented NOV. 15, 1910.

. Application sled octber 4, 1907. serial Nol 395,833.

To all whom it may concern:

Be it known that I, CHARLES L. A.. BRAS- sEUR, a citizen of the United States, and a resident of New York city, in the county of York, have invented a certain new and useful Improvement in Polychrome Screens and Processes .for Making the Same, of which 'the following is a specification.

rIhis invention relates to partycolored or polychrome screens for use in color photography and to a process for making the same, the primary object of the invention being to produce a grained screen having the grains of one color distributed thereon in a regular manner.

Another object is to obtain substantial ,regularity in the distribution of the diifer'- ently colored grains over the surface of the screen.

Other objects will appear hereinafter.

In my French Patent Number 364,132, dated March l, 1900, is indicated a method whereby photographs in natural colors, or in colors seeming such to the eye, may be obtained with one exposure and one development from negatives made on ruled or grained polychrome screens. In order to carry out this method successfully, it is necessary that the pattern on both the negative and the positive screens, plate or film be either symmetrically distributed in colors regularly recurrent, as is the case with the ruled screens made by the method indicated in my United States application for patent` .filed October 4, 1904, Serial Number 227 ,100,

i the diifusion of light purposely introduced in lieu of that motion, kshall be so slight as not to interfere with the'sharpness deemed necessary in a good photogra h. The reason for thisditl'usion of the ight is given in the above-named French atent.

In my -United States app ication Serial; Number 391,964, led on or about. September `9 1907, AI indicate how the"graine d screens may be made by cutting up line Y ments ofA plastic materlal and then convert?" ing these minute cylinders or prisms into spheres by rolling them between plates, and also h'ow these spheres can be used in making partycolored screens. i these methods, the grains have been thoroughly mixed, the resulti'nf :creen will have the grains distributed tnereon in so nearly a symmetrical arran ement as to meet all the requirements o method. But this .thoroughness of mixing is not possible with all grains, as some, by such handling, tend to break up into smaller" particles, inwhich case symmetry is ditlicult to obtain.

In order to obtain a sufficiently symmetrical l distribution under industrial conditions, and thus to avoid losses of great y quantities of screens owing to defective symmetry, the following method has been devised or invented, to wit: I take a sheet of paper or some other suitable support b which is coated with gum or other adhesive material which has been allowed to dry or harden, and print upon it from a copper plate 1n a regularly recurrent series of colors. 85.

The printing is done with a substance which will render the dots or points a adhesive, and while these dotsare yet in-this tacky condition, I dust on the support spheres of one of the colors which are'used on the 90 screen, as the red, for example. It is preferred that these spheres, which are marked R in Figure 3, should be of 'slightly smaller diameter than the spaces they are intended to fill in the finished screen in. order to allow the second operation to be more readily performed. After such dusting and after allowing the adhesive dots to dry or harden, the surplus spheres are allowed to roll'oif the support. The support b is then 100 placed on a suitable flat board or other support vand spheres of the other two colors, thoroughly mixed together, are allowed to run in and ill in the intervening spaces.

The paper is then rendered adhesive by means -of whatever agent, such as steam,

' heat, or other, will soften the gum or other .material employed. By thist'reatment, all "the spheres 4in contact with ithe paper or support b are made to adhere;, thJereto.V .The

'aper isaganallowed fzzorjfthe adesive to -hardenthe-s' Vplus spheres If, when using 60 the copying 65 are made to drop off the same. The spheres the red light only goes through the red are next transferred to glass or to acelluloid l dots H, so that, even if there is a symhhn or other support by means oi' heat and i pressure, the paper is removed by dissolv- `ing the adhesive material, and the surface is finished by means of heat and pressure; or, if necessarygvit can be sprayed over with thin Celluloid and then be polished by the means usually employed in the celluloid indust-ry. If necessary, the paper .covered with spheres can, before transferring, be pressed between hot plates in order to first. flatten the under side ofthe spheres. Or it may be treated in any of the ways described in my aforesaid appli-cation of September The result in all cases is a' patterned screen on glass, film, or other support, the

peculiarity of which is that the grains of one color are symmetrically distributed while the others, of one or more colors, are distributed with sufficient symmetry to answer all the needs of the case.

Instead of using a copperplate'to print the dots a, use may be made of photography in locating said dots on the paper or support Z). Thus, a glass plate can be coated with varnish which is then allowed to dry; on this a layer of sensitive album'en is spread (albumen and potassium bichromate). Then dry, this is printed under a subdivided' negative. The plate is ithen rolled over with an adhesive material nonsoluble in water, and is then soaked in water which will remove all the spluble albumen, leaving only albumen dots coated with adhesive matter. I Spheres of one color are then dusted on this, and a mixture of the other colors is made to ill the spaces left. The plate is then finished as in the first case described.

While it is possible to print other series of adhesive dots after the rst colored spheres are located, and thus to locate the second and even the third series of colored spheres `(which are not mixed together in such event), recourse to this costly expedient need only be had when absolute perfection is demanded.

lThe printed pattern on which the spheres or particles of other form or desired shape, are to'adhere can be varied, of course, from the hexagonal arrangement shown in Fig. 3. Thus, it can be printed so as to locate the spheres in parallel lines, and, in the case of black and white screens, it must be printed --so as to evenly distribute the black and ing, the dotted circles c indicating that the whole surface. is acted upon, though uietrical distribution, all red dots will rcceive the red light transmitted through the negative screen; Fig. Q represents, on an enlarged scale, the appearance of a grain screen in the viewing or positive colors, red (R), green (Gr) and blue-violet (B), wherein there is symmetrical distribution of colors; Fig. S is a fragmentary View showing a paper or other support Z) having a 'series of adhesive dots a thereon, and showing red spheres R as adhering to sundrysof said dots, and indicating, by the dotted circover with the third lot of colored spheres,

remove the surplus, and finish as above described by flattening out the grains or spheres. l

'What I claim as new and desire to secure by Letters Patent of the United States is- 1. The method, substantially as hereinbefore set forth, of making polychrome screens for color photography, consisting in providing -a support with tacky areas, dusting colored grains thereon and, when dry or hard, removing the surplus grains, then rendering the surface tacky, and dusting other colored grains thereon, and thereafter removing the surplus grains. v

2. A polychrome screen for color photography consisting of a support, grains of one color arranged thereon in symmetrical'disposition, and other grains intermingled in the spaces between said symmetrically arranged grains.

3. The method, substantially as hereinbefore set forth, of making polychrome screens forl color photography, consisting in printing a series of tacky dots on a support, covering the same with grains of one color, and removing thesurplus or unattached grains,

and in repeating the process for each set of grains to be added thereafter.

Signed at New York city in the county of New York and State of New York this third day of October A. D. 1907.

CHARLES L. A. BRASSEUR.

Witnesses HUGO Moon, R. W. BARKLEY. 

